Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41N—PRINTING PLATES OR FOILS; MATERIALS FOR SURFACES USED IN PRINTING MACHINES FOR PRINTING, INKING, DAMPING, OR THE LIKE; PREPARING SUCH SURFACES FOR USE AND CONSERVING THEM
  • B41N1/00—Printing plates or foils; Materials therefor
  • B41N1/24—Stencils; Stencil materials; Carriers therefor
  • B41N1/246—Stencils; Stencil materials; Carriers therefor characterised by the electroconductive means or additives

Definitions

• This invention relates to films for use as stencils in mimeograph printing and which comprise polypropylene resin and electro-conductive carbon black.
• the films exhibit excellent ink solvent resistance in mimeograph printing and uniform perforatability on being subjected to electrical discharge treatment.
• a film prepared by uniformly kneading a polyvinyl chloride resin, an electroconductive carbon black and additives such as a plasticizer and a stabilizer, and molding the resultant mixture has conventionally been used as a stencil employed in mimeograph printing.
• the film is used as a stencil by superposing the film on a base paper constituted by high quality paper bearing an electro­conductive layer comprising electroconductive carbon black and a binder, perforating the film by electrical discharge treatment and then peeling it off the base paper.
• a film comprising polyvinyl chloride resin gives off hydrogen chloride gas because of the heat generated when the film is perforated by the electrical discharge treatment, and therefore poses problems of hygiene and also of corrosion of the electrical discharge device being employed.
• a polyolefin resin such as polyethylene resin or polypropylene resin
• the film formed of such a resin does not generate gas having unpleasant odor, but on the other hand the use of polyethylene resin for forming the film used as a stencil raises the problem that the film is swollen by oils or solvents contained in printing ink; the film consequently becomes elongated during mimeograph printing, resulting in formation of wrinkles, and sharp prints cannot be obtained.
• polypropylene resin does not entail any great problem over ink solvent resistance during printing, but it does raise the problem that a composition to which a large amount of electroconductive carbon black has been added is difficult to mold into a film having a uniform thickness; as a result the perforating properties required for use as a stencil become non-uniform and, therefore, the amount of carbon black that can be added is limited.
• one aim of the present invention is to overcome the problems arising from non-uniform perforata­bility during electrical discharge treatment normally encountered when using a composition comprising a polypropylene resin and an electroconductive carbon black to form a film for use as a stencil in mimeograph printing.
• Another aim of the present invention is to provide a film for use as a stencil in mimeograph printing and which does not generate gas having unpleasant odor when the film is perforated by electrical discharge treatment; which has excellent ink solvent resistance during mimeograph printing; and which has uniform perforating properties during electrical discharge treatment even when a large amount of carbon black is incorporated in the film.
• the film according to the present invention for use as a stencil in mimeograph printing is prepared from a composition comprising from 70 to 90% by weight of a poly­propylene resin, from 30 to 10% by weight of an electro­conductive carbon black, and from 0.05 to 3 parts by weight, per 100 parts by weight of the total amount of the poly­propylene resin and electroconductive carbon black, of an organofunctional compound selected from organofunctional silanes, organofunctional titanates and organofunctional aluminates.
• the crystalline propylene homopolymer has a density of at least 0.903 g/cm3, preferably at least 0.904 g/cm3, and a crystallinity of at least 62% (calculated from the density), preferably 63 to 70%.
• the density is less than 0.903 g/cm3
• the ink solvent resistance is poor; and elongation of the film occurs during mimeograph printing, resulting in the formation of wrinkles, and unclear prints tend to be obtained. These defects may also occur in the case of using a copolymer of propylene with ethylene or the like.
• electroconductive carbon black examples include acety­lene black, furnace black, thermal black, specific furnace black (Ketjen Black, a registered trademark), and the like. These carbon blacks can be used alone or as mixtures thereof.
• the amount of the polypropylene resin used is from 70 to 90% by weight, preferably from 75 to 85% by weight, and the amount of the electroconductive carbon black used is from 30 to 10% by weight, preferably from 25 to 15% by weight, based on the total weight of the polypropylene resin and the electroconductive carbon black. If the amount of the electroconductive carbon black is less than 10% by weight, sufficient perforation cannot be obtained with electrical discharge treatment. On the other hand, if the amount thereof is more than 30% by weight, film forma­tion is difficult, the film obtained is brittle or the film breaks during electrical discharge treatment.
• mineral oils such as paraffinic, naphthenic or aromatic processing oils which are conven­tionally used as softening agents for rubbers, fluid paraffin, and vegetable oils such as castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil and peanut oil, can be added to the composition in an amount of from 0.1 to 25 parts by weight, preferably from 0.5 to 15 parts by weight, per 100 parts by weight of the polypropylene resin.
• the addition thereof can provide a film for use as a stencil in mimeograph printing which has good perforata­bility, even at high speed, during electrical discharge treatment, and no propensity to curl.
• the organofunctional compound selected from organo­functional silanes, organofunctional titanates and organo­functional aluminates which can be used in the present invention is a compound such as is used as a coupling agent in glass-fiber reinforced thermosetting resins and thermo­plastic resins.
• organofunctional silanes include vinyl triethoxysilane, vinyl trichlorosilane, vinyl tris( ⁇ -methoxyethoxy)silane, ⁇ -methacryloxypropyl­trimethoxysilane, ⁇ -glycidoxypropyltrimethoxysilane, ⁇ -(3,4-epoxycyclohexyl)ethyltrimethoxysilane, ⁇ -aminopropyl­triethoxysilane, ⁇ -aminodithiopropyltrihydroxysilane, N- ⁇ -(aminoethyl)- ⁇ -aminopropyltrimethoxysilane, N-bis­( ⁇ -hydroxyethyl)- ⁇ -aminopropyltriethoxysilane, ⁇ -chloro­propyltrimethoxysilane and ⁇ -mercaptopropyltrimethoxysilane.
• organofunctional titanates include isopropyl­triisostearoyltitanate, isopropyltridodecylbenzenesulfonyl­titanate, isopropyltris(dioctylpyrophosphate)titanate, tetraisopropylbis(dioctylphosphite)titanate, tetraoctylbis (ditridycelphosphite)titanate, tetra(2,2-diallyloxymethyl-­1-butyl)bis(di-tridycelphosphite)titanate and bis(dioctyl­pyrophosphate)oxyacetatetitanate, bis(dioctylpyrophosphate)­ ethylenetitanate.
• organofunctional aluminates include acetoalkoxyaluminumdiisopropylate.
• the organofunctional compound is used in an amount of from 0.05 to 3 parts by weight, preferably from 0.1 to 1.5 parts by weight, per 100 parts by weight of the total amount of the polypropylene resin and the electroconductive carbon black. If the amount of the organofunctional compound is less than 0.05 parts by weight, it is difficult to form the compositon into a film having a uniform thick­ness and its perforating properties consequently become non-uniform. On the other hand, if the amount thereof is more than 3 parts by weight, a beneficial effect from further addition cannot be expected, and extrusion to form a film cannot be conducted in a stable manner.
• the components described above are kneaded in a conventional mixing machine such as a Banbury mixer, rolls or a single- or twin-screw extruder, and the mixture obtained is subjected to film-forming processing.
• a conventional additive such as zinc stearate may be used.
• the film is molded by a T-die casting method, a tubular method using a circular die, or a like method.
• the thickness of the film according to the present invention for use as a stencil in mimeograph printing is preferably 10 to 30 ⁇ m. If the thickness is less than 10 ⁇ m, the film strength after perforation is poor; and if the thickness is more than 30 ⁇ m, the perforations are not sufficiently sharp, and clear prints cannot be obtained.
• the film according to the present invention for use as a stencil in mimeograph printing has the advantages that, since a polypropylene resin is used, gas having unpleasant odor is not generated when the film is perforated by an electrical discharge treatment and the ink solvent resistance is excellent, and as a result, there is no problem of film elongating during mimeograph printing, resulting in formation of wrinkles and consequent failure to obtain clear prints.
• a film having a uniform thickness can be obtained, and as a result, the film exhibits uniform perforatability during electrical discharge treatment.
• the resulting composition was extruded by T-die at a resin temperature of 200°C using an extruder having L/D of 24 and a diameter of 65 mm to obtain a film for use as a stencil in mimeograph printing and having a thickness of 20 ⁇ m.
• the molding speed was 18 m/min.
• the film was superposed on an electroconductive base paper, and perforated by electrical discharge treatment using an electrical discharge device ("GOM 690D", a product of Gakken Co., Ltd.), and peeled off from the base paper.
• the resulting stencil was set on a rotary printing press ("EP300", a product of Seiki Kogyo K.K.) and printing was conducted using an oily ink at a speed of 50 copies/min. 3,000 copies were printed over 3 hours, while checking the printing ink resistance every 1,000 copies by allowing to stand for 60 minutes in contact with a printing ink.
• the film for use as a stencil in mimeograph printing obtained was evaluated for uniform thickness, generation of gas having unpleasant odor, uniform perforations and sharpness of prints.
• a film for use as a stencil in mimeograph printing was prepared in the same manner as in Example 1 except that ⁇ -aminopropyltriethoxysilane ("A-1100", a product of Nippon Unicar Co., Ltd.) was used in place of N- ⁇ -(amino­ethyl)- ⁇ -aminopropyltrimethoxysilane.
• A-1100 a product of Nippon Unicar Co., Ltd.
• a film for use as a stencil in mimeograph printing was prepared in the same manner as in Example 1 except that a resin having a density of 0.903 g/cm3 ("Mitsubishi Norbrene FY3", a product of Mitsubishi Petrochemical Co., Ltd.) was used as the crystalline propylene homopolymer.
• a film for use as a stencil in mimeograph printing was prepared in the same manner as in Example 1 except that the amount of N- ⁇ -(aminoethyl)- ⁇ -aminopropyltri­methoxysilane was changed to 0.3 part.
• a film for use as a stencil in mimeograph printing was prepared in the same manner as in Example 4 except that the proportions of the crystalline propylene homo­polymer and the acetylene black were changed to 75% and 25%, respectively.
• a film for use as a stencil in mimeograph printing was prepared in the same manner as in Example 1 except that a propylene-ethylene copolymer having a density of 0.902 g/cm3 and anethylene content of 2.5% ("Mitsubishi Norbrene FW3", a product of Mitsubishi Petrochemical Co., Ltd.) was used in place of the crystalline propylene homopolymer.
• a film for use as a stencil in mimeograph printing was prepared in the same manner as in Example 1 except that paraffinic processing oil ("PW-90", a product of Idemitsu Kosan Co., Ltd.) was added to the composition in an amount 5 parts by weight per 100 parts by weight of the crystalline propylene homopolymer.
• PW-90 paraffinic processing oil
• a film was prepared in the same manner as in Example 1 except that N- ⁇ -(aminoethyl)- ⁇ -aminopropyltri­methoxysilane was not used.
• a commercially available film for use as a stencil in mimeograph printing made of polyvinyl chloride resin was subjected to perforation and mimeograph printing in the same manner as in Example 1.
• the film according to the present invention for use as a stencil in mimeograph printing does not generate gas having unpleasant odor during perforation, has excellent ink solvent resistance, and has uniform per­foration properties.

Landscapes

• Printing Plates And Materials Therefor (AREA)
• Inks, Pencil-Leads, Or Crayons (AREA)
• Compositions Of Macromolecular Compounds (AREA)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

Country Status (3)

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Citations (1)

• 1985
  • 1985-07-26 JP JP16556985A patent/JPS6227189A/ja active Pending
• 1986
  • 1986-07-25 EP EP86305757A patent/EP0210852A3/de not_active Withdrawn
  • 1986-07-26 CN CN198686105183A patent/CN86105183A/zh active Pending

Patent Citations (1)

Non-Patent Citations (1)

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